Method and system for hybrid energy management control

• US 20070251741A1
• Filed: 04/26/2006
• Published: 11/01/2007
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Lo, Chihsiung, Koch, Brian, Frisch, Damon, Kidston, Kevin, Stephens, George, Maiorana, Mario
• Granted Patent: US 7,900,726 B2
• Time in Patent Office: Days
• US Class Current: 180/65.290
• CPC Class Codes: B60K 6/44 Series-parallel type
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

A charging system for a hybrid vehicle comprises an internal combustion engine, an electric motor generator coupled to the internal combustion engine and operable to be driven as a generator to produce a charging voltage and a battery coupled to the electric motor generator and configured to receive a charge voltage. The charging system further comprises an engine control computer coupled to the internal combustion engine, the electric motor generator and the battery. The engine control computer is configured to determine a threshold CSFC, calculate an instantaneous CSFC, and initiate active charging of the battery if the instantaneous CSFC is less than or equal to the threshold CSFC.

Claims

1. A method for optimizing active charging of a battery in a hybrid vehicle comprising:

calculating a change in a state of charge of the battery;

determining a threshold CSFC using, at least in part, the change in the state of charge of the battery;

calculating an instantaneous CSFC; and

,

charging the battery if the instantaneous CSFC is less than the threshold CSFC.

2. The method of claim 1 wherein the step of determining a threshold CSFC further comprises:

determining a current vehicle speed; and

determining the threshold CSFC using the change in the state of charge of the battery and the current vehicle speed in conjunction with a lookup table.

3. The method of claim 1 wherein the step of determining a change in a state of charge further comprises:

determining a present state of charge of the battery; and

calculating a change in the state of charge battery by subtracting the present state of charge from a minimal state of charge.

4. The method of claim 3 further comprising the step of setting the minimal state of charge of the battery as the lowest state of charge that the battery can be at while still providing all vehicle electrical demands.

5. The method of claim 1 wherein the step of calculating an instantaneous CSFC further comprises calculating the instantaneous CSFC by dividing a brake specific fuel consumption by the product of a motor generator efficiency and a DC-to-DC converter efficiency.

6. The method of claim 1 further comprising the step of continuing to charge the battery until the instantaneous CSFC exceeds the threshold CSFC by a predetermined amount.

7. The method of claim 1 further comprising the step of preventing active charging if the change in state of charge exceeds a fixed amount.

8. A charging system for a hybrid vehicle comprising:

an internal combustion engine;

an electric motor generator operable to be driven as a generator to produce a charging voltage;

a battery coupled to the electric motor generator and configured to receive a charge voltage; and

an engine control computer coupled to the internal combustion engine, the electric motor generator and the battery, the engine control computer configured to;

determine a threshold CSFC;

calculate an instantaneous CSFC; and

initiate active charging if the instantaneous CSFC is less than or equal to the threshold CSFC.

9. The system of claim 8 wherein the engine control computer is further configured to determine the threshold CSFC further by:

determining a current vehicle speed; and

calculating the threshold CSFC using the change in the state of charge and the vehicle speed.

10. The system of claim 8 wherein the engine control computer is further configured to determine a change in the state of charge by:

determining a present state of charge; and

calculating a change in the state of charge by subtracting the present

state of charge from a minimal state of charge.

11. The system of claim 8 wherein the engine control computer is further configured to calculate the instantaneous CSFC by dividing a brake specific fuel consumption by the product of a motor generator efficiency and a DC-to-DC converter efficiency.

12. The system of claim 8 wherein the engine control computer is further configured to charge the battery until the instantaneous CSFC exceeds the threshold CSFC by a predetermined amount.

13. The system of claim 8 wherein the engine control computer is further configured to prevent active charging if the change in state of charge exceeds a fixed amount.

14. The system of claim 8 wherein the hybrid vehicle is a parallel hybrid vehicle.

15. The system of claim 8 wherein the hybrid vehicle is a serial hybrid vehicle.

16. The system of claim 8 wherein the hybrid vehicle is a start-stop hybrid vehicle.

17. A method for optimizing the charging of a battery in a hybrid vehicle comprising:

determining a threshold CSFC using a change in the state of charge of the battery and a current vehicle speed;

calculating an instantaneous CSFC using a measure of engine efficiency and a measurement of battery charging efficiency; and

charging the battery if the instantaneous CSFC is less than the threshold CSFC.

18. The method of claim 17 wherein the step of determining a threshold CSFC further comprises using the change in the state of charge of the battery and the current vehicle speed as inputs to a lookup table to determine the threshold CSFC.

19. The method of claim 17 wherein the step of determining a change in the state of charge further comprises:

determining a present state of charge of the battery; and

calculating a change in the state of charge by subtracting the present state of charge of the battery from a minimal state of charge of the battery, the minimal state of charge of the battery set as the lowest state of charge that the battery can be at while still providing all vehicle electrical demands.

20. The method of claim 17 wherein the step of calculating the instantaneous CSFC further comprises calculating the instantaneous CSFC by dividing a brake specific fuel consumption by the product of a motor generator efficiency and a DC-to-DC converter efficiency.